How do I send negative numbers or below zero in CW?

Sometimes when operating CW I want to send numbers that are negative. In particular when operating outdoors during the winter and someone asks the temperature, I would like to come back in CW with -5C. For some events like Freeze Your Butt Off, the temperature is a required part of the exchange. I realize that almost always the temperature in Fahrenheit will be above zero, but as a Canadian Ham I would prefer to use Celsius.

The best I have come up with so far is to send M5C, but I am not sure that this will be well understood.

• The rare occasions I have had to do that I just say something like minus 5 by actually sending MINUS. – K7PEH Dec 5 '17 at 23:05
• @K7PEH Yes, and that's an acceptable answer. I guess I am asking if there is generally accepted, shorter abbreviation. MINUS would do for one off rag chews. As part of the exchange in an operating event it would be quite long. – Malcolm VE2DDZ Dec 5 '17 at 23:08
• I have been in a lot of different CW contests and I have never had to report the temperature or anything else needing a minus sign. However, even if I did have to report it, it would more than likely be above zero so I personally get to ignore the problem. As I said, very rare for me to need a minus sign. The only special characters I use regularly are comma, question mark and slash. Of course, you could use the Kelvin temperature scale -- no negative temperatures at all. – K7PEH Dec 6 '17 at 0:36
• @JimMacKenzie Here either (QC), but I don't operate outdoors below -15C which is still above 0F. I should have put that in the question. PS. I'm well aware of Saskatchewan temperatures - I grew up in Fort Qu'Appelle and get back to visit Regina regularly. – Malcolm VE2DDZ Dec 6 '17 at 20:08
• @MalcolmVE2DDZ Next time you're in town, be sure to ping 147.120+ VE5YQR. My callsign is VE5EIS, and if you talk to VE5SDH (she's easier to reach), she can relay a message if you can't find me live. – Jim MacKenzie VE5EV Dec 6 '17 at 20:31

According to Wikipedia there is a code for the hyphen or the minus symbol, − · · · · −. However very few hams are likely to recognize it. In the meantime I would suggest sending "MINUS" or "NEG".

If "Freeze Your Butt Off" ever grows to become a big-time contest, then contesters will work out some efficient way of communicating negative numbers. (Or maybe most everyone will just send "dah" as the "cut number" for zero, similar to the way most signal reports in Morse code contests are "5NN".)

• FYBO is not such a big deal since the rules stipulate temperature in Fahrenheit and I'm not going to be on the air long in temperatures below 0F. I think I prefer NEG to MINUS, it has better rhythm :-) – Malcolm VE2DDZ Dec 5 '17 at 23:32
• Seems to me FYBO should get used to using -....- since it's a lot more efficient than NEG or MINUS (and we don't use BELOW with Celsius). – Jim MacKenzie VE5EV Dec 6 '17 at 14:38
• A rarely-used punctuation code will never catch on for contest use---too confusing for newbies. – rclocher3 Dec 6 '17 at 16:16
• @rclocher3 Send -5, NEG5, -5 ... they'll get the gist fast. – Jim MacKenzie VE5EV Dec 6 '17 at 20:32

The dash (-....-) would be the usual way to denote negative numbers. If some HAM does not easily decode this: well, it's time to improve your capabilities :)

You can use Kelvin as temperature scale. https://en.m.wikipedia.org/wiki/Kelvin

• The question is how to send negative numbers in CW with temperatures as an example use case. The suggestion to use Kelvin doesn't address how to send negative numbers in general. Nor is reporting temperatures in K really a viable alternative when the purpose is to transmit a readily understood response to a question about the ambient temperature for the same reason that none of my portable thermometers, analog or digital, read in K. – Malcolm VE2DDZ Jan 15 '18 at 19:40